Installation level including insulation - influence on the insulation of the exterior wall?

Hi,

as part of my renovation project, the exterior wall of the "existing building" is being insulated with 10cm mineral fiber insulation boards (WLG035). The exterior wall is a 24cm wall made of Liapor stones.

Until now, there has only been interior insulation of 5cm Styrofoam.

As part of the renovation, I now want to install an installation layer on the interior wall. In one place because I have to (heating pipes with insulation >> 10cm) and in another place because I hope the electrical installation will be much easier instead of chasing grooves, etc. Also, the statics must be taken into consideration here. So far, everything was within the 5cm Styrofoam.

That means I want to install an installation layer on the interior wall, 4cm and 10cm thick, which will also be insulated (also with a mineral insulating material) + 15mm OSB + 12.5mm drywall.

Is there anything to consider or clarify regarding the insulation on the exterior wall? Or can I do it without any problems?

I have read various reports about "shift of dew point," etc., and am therefore uncertain...

Best regards,
Chris

As part of my conversion project, the exterior wall of the "existing building" is being insulated with 10cm mineral wool insulation boards (WLG035).

Why insulate so poorly?

That means I want to install an installation level on the interior wall, 4cm and 10cm thick, which will also be insulated (also with a mineral insulation material) + 15mm OSB + 12.5mm drywall.

And here’s the question, what is the nonsense with the interior insulation if you are already insulating from the outside?

Maybe I need to go into a bit more detail.

I have added a storey to part of the building (timber frame, yellow area). Here, a 60mm deep installation level is already planned. The load-bearing wall between the yellow and grey area (grey-yellow dashed) also consists of 240mm Liapor blocks with a timber frame built on top. The blocks are no longer in the exterior area. Green: Here are 2 dormer roofs with an interior stud wall which will also be insulated. Exterior wall Liapor. Couldn’t do otherwise because of the parapet height, etc. In the grey-red dashed area, the roof continues. The roof itself is insulated. Below is a heated room.

For the red-marked area, I have to make a stud wall/installation level because heating pipes and water lines run there.

My question refers to the area following that (actually the entire grey area).

My intention is less to achieve something with interior insulation but to have a clean installation level. Anyone who knows Liapor blocks knows that they are not so easy to work with. Also, I wouldn’t have to worry about anything regarding statics, etc. Likewise, I would then have the same wall structure in all rooms (OSB + drywall).

Why do I only insulate 10cm on the outside? Because that’s how the energy consultant calculated it.

Correct would be:
Likewise, I would then have the same sheathing on the inside of the wall in all rooms (OSB + gypsum board).

My intention is less to achieve something with the interior insulation but rather to have a clean installation level.

I understand clean installation level. You can also simply leave out interior insulation if it serves no purpose anyway.

Why do I insulate only 10cm on the outside? Because that's how the energy consultant calculated it.

So minimum insulation. As a tip: The fixed costs are there anyway (craftsmen, scaffolding, plaster etc.). A thicker insulation only makes a marginal difference in costs (a few percent surcharge), since everything else remains the same. Hence my question. On the topic of dew point shift: ubakus - you can plan a lot yourself ==> but it looks bad with interior insulation without further measures (unless you simply leave out the interior insulation). only with air layer with interior insulation

Ok thanks for the tip. I entered my intended wall design. For me, the U-value with the insulation in the installation layer is slightly better than without...

Basically, my question is not about "whether it makes sense or not" but more about:
Could this create some effect that I do not want or that leads to problems.

The OSB interior wall is also not executed as a vapor barrier. That means electrical outlets and holes are not sealed airtight...